Process for preparing a gel element

ABSTRACT

The present invention relates to a process for preparing a gel element comprising a perfume and to a process for preparing an air freshening device comprising such a gel element.

The present invention relates to a process for preparing a gel elementcomprising a perfume and to a process for preparing an air fresheningdevice comprising such a gel element.

Various devices for perfuming an atmosphere are known. Such devices maysimply fragrance the air, or may be used to mask bad odours.

Many different types of air freshener devices have been proposed. Oneparticular type is described in WO 96/05870 and WO 00/24434. This devicecomprises a gelled element resulting from the cross-linking between afunctionalised liquid polymer and a cross-linking agent in the presenceof a perfume base. In order to prepare such an element a liquidfunctionalised polymer is mixed with a cross-linking agent in thepresence of a perfume. The polymer crosslinks in the presence of theperfume to form a gel which encloses the perfume, preferably in athree-dimensional network. Such a gel can be formed in a recess in asubstrate to form an air freshener device, or can simply be used as ablock. This gel has an attractive appearance. A large proportion ofperfume base, for example up to 90 wt %, especially 60 to 90 wt %, maybe used which provides a gel element of a small size.

In practice, the volume of crosslinking agent is small compared with thevolume of perfume and polymer. For example, the crosslinking agent maybe used in an amount of up to 2 vol % with respect to the total volumeof components which are mixed together before gelling. While it ispracticable to mix the perfume and polymer together to form ahomogeneous mixture and then mix in the crosslinking agent, we havefound that such an arrangement is not completely satisfactory because itis difficult to control the flow of the crosslinking agent in view ofits relatively small volume.

We have therefore found that it is appropriate to equalise to a certainextent the flow rates of the different premixes into the final mixingstep. Accordingly it is possible to form the perfume by conventionalmethods and then mix some of the perfume with the polymer and theremainder of the perfume with the crosslinking agent. The two mixturescan then be mixed together to form a mixture which is able to gel. Sincethe perfume is split between the two mixtures, the mixture containingthe crosslinking agent has a greater volume than the volume of thecrosslinking agent by itself, and therefore a greater flow rate whichcan easily be controlled.

We have now found that while this arrangement is satisfactory when theproduction line starts, it is not entirely satisfactory after theproduction line has been running for some time. It has been found thatthe gelling time of the mixture, i.e. the time required for a gel whichdoes not flow to be formed, tends to rise over time. This can causesignificant problems as the manufacturing shift progresses, especiallyat the end of a shift when a machine is operating. For example, if thegelling time of the mixture increases such that it is longer than thetime that the containers containing the perfume element are on theproduction line, the gel may not have solidified to an acceptable extentand may still at least partly be in liquid form when the containers areremoved from the line. This liquid can spill out of the containersleading not only to wastage but also to other problems such as foulingof the production line and local environment.

The present invention seeks to overcome this problem by providing aprocess in which the setting time of the mixture is reasonably constantover the time that a production machine is likely to operate, forexample an eight hour shift or the length of time that the mixtures arestored before they are used, which is typically about four hours.

The present invention provides a process for preparing a gel elementcomprising a perfume which comprises:

-   -   i. forming a premix A of a liquid functionalised polymer and        perfume components A;    -   ii. forming a premix B of a crosslinking agent able to crosslink        said liquid functionalised polymer and perfume components B; and    -   iii. mixing premix A and premix B such that said liquid        functionalised polymer is crosslinked by said crosslinking agent        in the presence of a perfume; wherein perfume components A are        different from perfume components B, perfume components A do not        substantially react with said liquid functionalised polymer and        perfume components B do not substantially react with said        crosslinking agent.

Perfumes usually contain components which react with either or both ofthe liquid functionalised polymer and the crosslinking agent.Accordingly in the process of the present invention the liquidfunctionalised polymer and crosslinking agent are mixed with differentparts of the perfume, namely perfume components A and perfume componentsB, before they are mixed together. Thus the liquid functionalisedpolymer and crosslinking agents are not simply mixed with the sameperfume composition. Instead the final perfume composition for thegelled element is determined, and different components of thecomposition are mixed with the liquid functionalised polymer and withthe crosslinking agent. It has surprisingly been discovered that byensuring an appropriate separation of perfume components, the aboveproblem can be solved to a practical extent or even completely avoided.It is, of course, possible for some individual components which do notsubstantially react with either the liquid functionalised polymer or thecrosslinking agent to be present in both perfume components A andperfume components B.

The perfume used in the process of the present invention is typically ananhydrous perfume, for example comprising less than 1 wt % water,especially less than 0.5 wt % water, more especially less than 0.1 wt %water and preferably comprising no water, and comprises a mixture ofdifferent ingredients. The perfume may simply provide a fragrance or itmay provide a deodorising effect. While the precise ingredients of anyparticular perfume are often the trade secret of a Fragrance Supplier,it is well known that perfume ingredients are typically volatilecompounds such as esters, alcohols, aldehydes and ketones. We have foundthat functionalised polymers and crosslinking agents can react withcertain perfume ingredients. The rate of reaction may be relativelyslow, so while this may not be a problem at the start of the productionrun, after the perfume ingredients have been mixed with thefunctionalised polymer and/or crosslinking agent for some time, forexample after a few hours, some reaction will have occurred with some ofthe perfume components. This may undesirably affect the perfume so itsfragrance is not constant over the full production run. Furthermore itwill use up some of the functionalised polymer and/or crosslinkingagent, which results in a reduction in the concentration of reactivesites of the functionalised polymer and/or the crosslinking agent afterthe production run has proceeded for some time. We have found that thisleads to the increased setting time.

Apart from the splitting of the perfume into perfume components A andperfume components B, the process of the present invention isessentially as described in WO 96/05870 and WO 00/24434, which areherein incorporated by reference.

The liquid functional polymer possesses one or more functional groups.The crosslinking agent possesses two or more complimentary functionalgroups. The mixtures of these two compounds gives, in the presence of aperfume base, a reaction product enclosing the perfume base which canthen emanate to the atmosphere to provide an air freshening effect. Toobtain a three-dimensional network it is, however, necessary for theliquid functional polymer to have at least two functional groups permolecule.

The liquid functionalised polymer is one which is liquid at roomtemperature (20° C.) and which generally has a viscosity of not morethan 5,000 poise at 25° C., preferably from 250 to 1,000 poise. Theliquid functionalised polymer should be soluble in the perfume base. Oneor more liquid functionalised polymers may be used.

Suitable functional groups are, for example, carboxylic acid, anhydrideor acid chloride groups as well as amine and alcohol groups. The polymercan be produced by adding functional groups to any polymer which iscapable of functionalisation, or the polymer can be one which inherentlycontains functional groups, either pendent on the main chain, optionallywith intervening spacer groups, or in the main chain. Preferred polymerswhich can be functionalised are polyolefins, particularly those derivedfrom mono- or di-olefins containing, prior to functionalisation, atleast one and preferably more than one vinyl group.

According to a preferred embodiment of the invention, the polymer is aderivative of butadiene, isoprene or chloroprene. Preferably the polymeris maleinised polybutadiene which may, for example, have a molecularweight of from 5000 to 20,000, or maleinised polyisoprene which may, forexample, have a molecular weight of from 200,000 to 500,000. Suchpolymers are commercially available materials. Examples are disclosed inEP-A-23,084. A preferred polymer is sold under the trademark Lithene bySynthomer. A particularly preferred Lithene polymer is Lithene N4-900010MA, which is a maleinised polybutadiene wherein the molecular weightof the polybutadiene before maleinisation is about 9000 and whichcontains 10 parts of maleic anhydride per 100 parts of polybutadiene.Lithene N4-B-10MA has also been found to be particularly suitable.

The crosslinking agent possesses two or more complementary functionalgroups to the functional groups on the liquid functionalised polymer.The complementary functional groups may be, for example, carboxylicacid, anhydride or acid chloride derived groups or amine or alcoholgroups. For example, if a liquid polymer possesses carboxylic acid,anhydride or acid chloride functionality, the crosslinking agents mayhave amine or alcohol functions, and vice versa. The crosslinking agentcontains two, three or more functional groups. Preferably, however, itcontains only two functional groups.

The crosslinking agent should be soluble in the perfume base. One ormore crosslinking agents may be used. Examples of suitable crosslinkingagents are dihydroxy polybutadiene, alkoxylated primary amines,alkylpropyldiamines having an ethoxylated or propoxylated fattyaliphatic chain, diethanolamine, diethylenetriamine,polyoxyalkylenediamines and alkoxylated primary fatty amines. Forexample the crosslinking agent may comprise one or more diamines and/ortriamines, in particular one or more polyoxyalkylene amines, inparticular diamines and triamines, such as polyethoxy diamines andtriamines and/or polypropoxy diamines and triamines. Suitableethoxylated primary amines are oleyl amines possessing two moieties ofethylene oxide per molecule.

Examples of alkylpropyldiamines having an ethoxylated or propoxylatedhigher aliphatic chain are those sold under the trademark Dicrodamet byCroda Chemicals Limited.

Examples of polyoxyalkylene diamines and/or triamines are polypropoxydiamines, polypropoxy triamines and polyethoxydiamines, particularlythose sold under the trademark Jeffamine by Huntsman Corporation, forexample Jeffamine D-400, Jeffamine D-2000, Jeffamine T-403 and JeffamineEDR-148.

Further useful crosslinking agents are oleylamines or cocoamines having2 to 5 ethylene oxide units per molecule, such as those sold under thetrademark Crodamet by Croda Chemicals Limited, for example Crodamet 02and Crodamet C5.

Additional useful crosslinking agent is polybutadiene having ahydroxylic function known as HFPB, obtainable from Revertex ltd. Thiscrosslinking agent is especially suitable for use with maleinisedpolybutadiene.

Another suitable crosslinking agent is an amine terminated liquidbutadiene/acrylonitrile copolymer, such as Hycar CTBN 1300×21,obtainable from B.F. Goodrich.

It is possible to use a mixture of two or more crosslinking agentshaving different reaction times with the liquid functionalised polymerin order to control the setting time of the gelled element.

The functionalised liquid polymer and crosslinking agent can be used inany molar ratio. Desirably, however, the molar ratio is from 3:1 to0.5:1, preferably from 1.5:1 to 1:1.5, more preferably about 1:1, basedon the molar ratio of the functional groups which are present. Ingeneral it is preferred to minimise the amount of unreactedfunctionalised polymer and crosslinking agent in the gelled element.

Catalysts can be included in premix A, premix B or in a further premixto assist in the gel formation. Examples of catalysts are tertiaryamines, for example DAMA 1010 obtainable from Albemarle SA, and JeffcatTD 100 or Jeffcat DMP, obtainable from Huntsman Corporation

In general the mixture which gels comprise up to 90 wt % perfume base,especially 60 to 90 wt %, more especially 75 to 85 wt %, based on thetotal weight of the mixture. It also desirably comprises 8 to 35 wt %,especially 12 to 25 wt %, more especially 15 to 20 wt %, functionalisedliquid polymer, based on the total weight of the mixture, and desirablyalso comprises 0.5 to 20 wt %, especially 0.5 to 6 wt %, more especially0.7 to 4 wt %, crosslinking agent, based on the total weight of themixture.

Further components can also be included in premix A, premix B or in afurther premix. Such components can include, for example, additionalperfume components, solvents, bitrex and dyes.

The perfume is a mixture of volatile liquid ingredients of natural orsynthetic origin. The nature of these ingredients can be found inspecialised perfumery books, for example in S. Arctander, Perfume andFlavour Chemicals, Montclair, N.J., USA, 1969. In order to carry out theprocess of the present invention, it is usual to carry out an initialstep of devising a perfume having the desired fragrance. This is aroutine operation which can be carried out by a Fragrance House.

In general it is the crosslinking agent which is able to react with someof the perfume components, whereas the liquid functionalised polymerusually does not appreciably react during the timescale of a productionshift. In this case, therefore, those components of the perfume whichreact or are considered likely to react with the crosslinking agent formthe basis of premix A. The remaining components which do not react orare considered unlikely to react with the crosslinking agent may formpremix B. However, it is perfectly possible, and indeed usual, for someof these components which do not react with the crosslinking agent to beadded to premix A. This may be useful to control the relative volumes ofthe premixes.

If the liquid functionalised polymer, but not the crosslinking agent, isable to react with some of the perfume components, those components ofthe perfume which react or are considered likely to react with theliquid functionalised polymer form the basis of premix B. The remainingcomponents which do not react or are considered unlikely to react withthe liquid functionalised polymer may form premix A. Again, it isperfectly possible for some of these components which do not react withthe liquid functionalised polymer to be added to premix B.

Another way of proceeding is to determine the ingredients of the perfumeand simply to take those a few of the components which are known not toreact with the crosslinking agent to form premix B or which are knownnot to react with the liquid functionalised polymer to form premix A.All of the other components are then used to form premix A or premix Brespectively.

Individual perfume components which do not react with either the liquidfunctionalised polymer or the crosslinking agent may, of course, beincluded in either or both of premix A and premix B.

In general it has been found that the aldehydes are capable of reactingwith either the liquid functionalised polymer or the crosslinking agent.It is usual, therefore, for substantially all of the aldehydes to bepresent in premix B or premix A respectively. Similarly it has beenfound that ketones often react with the liquid functionalised polymer orcrosslinking agent, although their rate of reaction is less than that ofthe aldehydes and some ketones do not react for steric reasons. We havefound, therefore, that it is desirable for the ketones also to bepresent in the premix A or premix B which contains the aldehydecomponents. We have also found that alcohols, in particular primaryalcohols, often react with the liquid functionalised polmyer orcrosslinking agent. It is desirable, therefore, that the alcohols, or atleast the primary alcohols and optionally secondary alcohols and/ortertiary alcohols, are present in the premix A or premix B respectively.It is particularly desirable for the premix A or premix B not to containaldehydes, and preferably also not to contain ketones, when the liquidfunctionalised polymer or crosslinking agent, respectively, containsamine groups.

In a preferred embodiment where the liquid functionalized polymer is amaleinised polybutadiene and the crosslinking agent is one or morepolyoxyalkylene diamines, it has been found that aldehydes in particularcan react with the crosslinking agent. It is usual, therefore, forsubstantially all of the aldehydes to be present in premix A. Similarlyit has been found that ketones also react with the crosslinking agent,although their rate of reaction is less than that of the aldehydes. Wehave found therefore that it is also desirable for ketones to be presentin premix A, which contains the aldehyde components. It has also beenfound that primary alcohols will react with the maleic anhydridemoeities of the liquid functionalised polymer and it is usual thereforefor substantially all primary alcohols to be present in premix B.

In the present invention it is necessary for the perfume components Aand perfume components B not to substantially react with the liquidfunctionalised polymer and crosslinking agent respectively. By this wemean that the components within each premix do not appreciably reacttogether before each batch is fully used. Clearly this will depend on acertain extent to the time taken for each batch of premix to be fullyused and the gelling time allowed on the production line. In general,however, each premix is stable at room temperature (20° C.) for at least2 hours, preferably at least 4 hours, more preferably at least 6 hoursand most preferably at least 8 hours.

By stable we mean that substantially no reaction occurs between theperfume components and the remaining components of the premix duringthis period. It is, therefore, possible for premix A and/or premix B tocontain some fragrance components which are capable of reacting slowlywith the liquid functionalised polymer or crosslinking agent,respectively, but which do not appreciably react within the time thatthe premixes are stored before use. Alternatively it is, of course,possible for the premix A or premix B to contain small quantities ofcomponents which react with the liquid functionalised polymer orcrosslinking agent, respectively, so long as these do not appreciablyreduce the amount of liquid functionalised polymer or crosslinking agentwhich is available for reaction. If any reaction does occur, thereaction only occurs to an extent that the gelling time to achieve asolid, non-flowable gel increases only slightly, for example by up to20%, preferably up to 10%, more preferably up to 5%. For example, if theinitial gelling time at the beginning of a production run is 6 minutes,desirably the gelling time increases at most to 7 minutes 12 seconds,preferably at most to 6 minutes 32 seconds and more preferably at mostto 6 minutes 18 seconds. These times are all significantly shorter thanthe increased gelling time of about 10 minutes which can be achieved ifthe perfume components are not split between the different premixes.

Desirably the premix A and/or premix B contain less than 1 wt %,preferably less than 0.5 wt % of components which react with the liquidfunctionalised polymer or crosslinking agent respectively. Moredesirably, the premix A and/or premix B contains no aldehydes and/orketones and/or primary alcohols as appropriate.

We have also found that the process of the present invention cansurprisingly reduce the formation of undesirable side products which canotherwise be formed during the process. For example, it was previouslynoticed that certain premixes could become cloudy, and even lack phasestability. We have now determined that this was due to certain perfumecomponents, in particular aldehydes, reacting with groups on the liquidfunctionalised polymer or crosslinking agent, in particular aminegroups, especially primary amine groups, to form a substituted imine andwater. This water is not usually miscible with the anhydrous perfumebase and hence the perfume base becomes cloudy. In extreme situations,the water can even form a second phase. In some cases certaincomponents, such as the substituted imines, can precipitate fromsolution which can cause blockages in the production machinery. Theprocess of the present invention surprisingly also overcomes thisdisadvantage since the in situ formation of water and other componentssuch as imines is substantially avoided.

Desirably the mixture gels (i.e. forms a non-flowable solid) in step iiiin less than 8 minutes during the entire production run, preferably from4 to 8 minutes, more preferably from 6 to 7 minutes.

The weight ratio of premix A to premix B is desirably from 2:1 to 8:1,for example from 3:1 to 6:1, especially from 4:1 to 5:1. The weightratio of perfume components A to perfume components B is desirably from2:1 to 6:1, preferably from 3:1 to 5:1.

The gel element is desirably formed by adding the mixture of premix Aand premix B to a mould, for example a recess in a substrate, andallowing the mixture to gel. Examples of suitable substrates and formsfor the recess are given in WO 00/24434.

The present invention is further described in the following Examples.

EXAMPLES Comparative Example 1

The following fragrance was prepared: Ingredient % w/w Isobornyl acetate25.00 Dihydromyrcenol* 25.00 tertiary-4-Butylcyclohexyl 15.00 acetateOrange oil terpenes 10.00 Terpinyl acetate 4.00 Eucalyptus oil 4.00Isopentyrate** 3.00 Juniperberry oil 2.50 Lavandin oil 2.00 AllylCaproate 2.00 Dynascone** 1.00 alpha-iso-Methyl ionone 1.00 Geranium oil1.00 Applinate** 1.00 Verdox* 1.00 n-Dodecanal 0.50 2-methyl undecanal0.50 Coriander oil 0.50 Rosemary oil 0.50 Galbanum oil 0.252,4-Dimethylformyl-3- 0.20 cyclohexene Oxane** (50% in 0.05triethylcitrate) 100.00*Origin: International Flavors & Fragrances Inc.**Origin: Firmenich S.A.

A cross-linking composition was prepared comprising 8.00 g JeffamineD-400 and 4.40 g Jeffamine EDR-148.

Premix A was prepared by mixing 14.26 g of Lithene N4-B-10MA and 53.68 gof the entire fragrance in a closed 120 ml glass powder jar using amagnetic stirrer until the Lithene had completely dissolved. Premix Bwas prepared by mixing 1.02 g of the formerly prepared cross-linkingcomposition and 14.92 g of the entire fragrance in a 20 ml glass vial.The time was then recorded (t=0).

After 10 minutes had elapsed 16.2 g of the Lithene/perfume mixture wastransferred to a 50 ml glass beaker, and continually mixed with amagnetic stirrer. 3.8 g of the perfume/cross-linking composition wasthen added under constant stirring. The setting time of the gel thusproduced was then measured.

This process was repeated when approximately 30 minutes, 4 hours andseven hours had elapsed. The gel setting times recorded are shown inTable 1. TABLE 1 Gel Setting Elapsed Time Time 10 minutes  8 min 12 sec30 minutes  9 min 40 sec  4 hours 11 min  5 sec  7 hours 13 min  5 sec

Example 2

The same fragrance composition of Comparative Example 1 was prepared astwo separate compositions, Perfume Components A and Perfume ComponentsB, in which all of the aldehydes and ketones were in Perfume ComponentsA.

Perfume Components A Ingredient % w/w Isobornyl acetate 25.00Dihydromyrcenol* 25.00 Orange oil terpenes 10.00 Terpinyl acetate 4.00Eucalyptus oil 4.00 Juniperberry oil 2.50 Lavandin oil 2.00 Dynascone**1.00 alpha-iso-Methyl ionone 1.00 Geranium oil 1.00 n-Dodecanal 0.502-methyl undecanal 0.50 Coriander oil 0.50 Rosemary oil 0.50 Galbanumoil 0.25 2,4-Dimethylformyl-3- 0.20 cyclohexene Oxane** (50% in 0.05triethylcitrate) 78.00*Origin: International Flavors & Fragrances Inc.**Origin: Firmenich S.A.

Perufme Components B Ingredient % w/w Tertiary-4-Butylcyclohexyl 15.00acetate Isopentyrate** 3.00 Allyl Caproate 2.00 Applinate** 1.00 Verdox*1.00 22.00*Origin: International Flavors & Fragrances Inc.**Origin: Firmenich S.A.

Premix A was prepared by mixing 14.55 g of Lithene N4-B-10MA and 54.78 gof Perfume Component A in a closed 120 ml glass powder jar using amagnetic stirrer until the Lithene had completely dissolved. Premix Bwas prepared by mixing 1.04 g of the cross-linking composition (as inComparative Example 1) and 15.22 g of Perfume Component B fragrance in a20 ml glass vial. The time was then recorded (t=0).

After 10 minutes had elapsed 16.2 g of the Lithene/perfume mixture wastransferred to a 50 ml glass beaker, and continually mixed with amagnetic stirrer. 3.8 g of the perfume/cross-linking composition wasthen added under constant stirring. The setting time of the gel thusproduced was then measured.

This process was repeated when approximately 30 minutes, 4 hours andseven hours had elapsed. The gel setting times recorded are shown inTable 2. TABLE 2 Elapsed Time Gel Setting Time 10 minutes 7 min 31 sec30 minutes 7 min 17 sec  4 hours 7 min 40 sec  7 hours 8 min 30 sec

1. A process for preparing a gel element comprising a perfume whichcomprises the steps of: i. forming a premix A of a liquid functionalisedpolymer and perfume components A; ii. forming a premix B of acrosslinking agent able to crosslink said liquid functionalised polymerand perfume components B; and iii. mixing premix A and premix B suchthat said liquid functionalised polymer is crosslinked by saidcrosslinking agent in the presence of a perfume; wherein perfumecomponents A are different from perfume components B, perfume componentsA do not substantially react with said liquid functionalised polymer andperfume components B do not substantially react with said crosslinkingagent.
 2. A process according to claim 1 wherein the crosslinking agentcomprises one or more diamines.
 3. A process according to claim 2wherein the crosslinking agent comprises one or morepolyoxyalkylenediamines.
 4. (cancelled)
 5. (cancelled)
 6. A processaccording to claim 1 wherein the liquid functionalised polymer comprisescarboxylic, anhydride or acid chloride groups.
 7. A process according toclaim 1 wherein the liquid functionalised polymer is a maleinisedpolybutadiene and/or polyisoprene.
 8. A process according to claim 1wherein the weight ratio of premix A to premix B is from 2:1 to 8:1. 9.A process according to claim 1 wherein the weight ratio of perfumecomponents A to perfume components B is from 2:1 to 6:1.
 10. A processaccording to claim 1 wherein the mixture gels in step iii in less than 8minutes during the entire production run.
 11. A process according toclaim 1 wherein premix A is stable at room temperature (20° C.) for atleast 4 hours.
 12. A process according to claim 1 wherein premix B isstable at room temperature (20° C.) for at least 4 hours.
 13. A processaccording to claim 1 wherein the gel element is formed in a recess in asubstrate to form an air freshening device.